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  • Control of phase transformation during processing of partially bainitic multi-component strip steels for controlling the work hardening characteristics


The project should help to calculate mechanical properties of multi-component and multiphase steels from the chemical composition and the parameter of the production process. The considered steel grades were TRIP steels, consisting mainly of a mixture of bainite, ferrite and retained austenite.

The project aims at two coupled models: A model for phase transformation under the prevailing conditions of technical continuous annealing and hot strip processes with special emphasis on the bainite transformation, and a model for work hardening that will provide additional information on damage processes resulting from specific multi-component microstructures. These models are calibrated by experimentally determined transformation kinetics and mechanical properties.

Progress has been made concerning the growth of ferritic bainite from carbon-enriched austenite. But, due to erratic nucleation processes, it is not yet possible to calculate the phase fractions from first principles. So analysis of experimental data remains important. A quantitative model allows the calculation of transformation kinetics from thermodynamic and experimental parameters.

Extensions to the common law of mixture have been made by modeling the mechanical properties. The multiphase strength is computed by using a self-consistent strain model (SCSM). A transformation plasticity model (TPM) of retained austenite in martensite has also been added. Both the SCSM and the TPM models have been incorporated within an incremental plasticity algorithm and this is interfaced to a finite deformation FEM code. The resulting MMM_FEM model has been applied to the simulation of tensile testing of steel strips.

Additional information

Authors: SELLGER R, TKS, Duidburg (DE);ÅGREN J, KTH, Stockholm (SE);HILLERT M, KTH, Stockholm (SE);HÔGLUND L, KTH, Stockholm (SE);BIANCHI J, CSM, Rome (IT)
Bibliographic Reference: EUR 20582 EN (2003), 111 pp. Euro: 25.00
Availability: EUR-OP reference: KI-NA-20582-EN-S Available from EUR-OP sales agents URL:
ISBN: ISBN: 92-894-5153-X
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